THE PRESENT INVENTION relates to a vehicle seat and more particularly, relates to a vehicle seat intended for use in a motor vehicle such as a motor car.
It has been appreciated that if a motor vehicle, such as a motor car, is involved in a rear-end collision, or rear impact,xe2x80x94that is to say if a following vehicle runs into the back of the carxe2x80x94the occupants of the struck car often suffer from neck injuries.
It is to be understood that during a rear-end collision of this type, the vehicle that is struck is subjected to a forward acceleration. This imparts a forward acceleration to the seats of the vehicle. The squab and the back of each occupied seat engage the posterior and torso of the occupant of the seat and impart a substantial acceleration to the posterior and torso of the occupant. However, no corresponding acceleration is immediately imparted to the head of the occupant. The head is a part of the body that has substantial mass, and consequently the head has substantial inertia.
Thus, whilst the posterior and torso of the occupant of the vehicle are accelerated forwardly as a result of die rear-end collision, the head of the occupant of the vehicle initially remains stationary. This causes the neck initially to adopt a xe2x80x9cSxe2x80x9d-shaped configuration as the lower part of the neck moves forwardly, whilst remaining vertical, and the upper part of the neck remains in its initial position. Subsequently, the head begins to rotate, and the neck then occupies a curved configuration. The head subsequently moves forwardly. Research has shown that xe2x80x9cwhiplashxe2x80x9d injuries may occur when the neck adopts the xe2x80x9cSxe2x80x9d-shaped configuration, if the head is moving, relative to the torso, at a substantial speed.
The present invention seeks to provide an improved vehicle seat in which the risk of xe2x80x9cwhiplashxe2x80x9d injuries occurring to the occupant of the seat during a rear-end collision are reduced.
According to this invention there is provided a vehicle seat, the seat comprising a squab and a back, the back being mounted for pivotal movement, relative to the squab, about a predetermined pivotal axis, the back being provided with a frame supporting a head-rest, the said frame being movable between a lower position and an upper position, the head-rest carried by the frame being located a greater distance from the top of the back of the seat when the frame is in the elevated position, means being provided to move the frame from the lower position to the upper position in response to said rearward pivotal movement of the back of the seat about the predetermined pivotal axis.
Preferably the means to cause the framework to move from the lower position to the upper position comprise a Bowden cable, the core of which is connected to move the said frame upwardly against a spring bias when the core of the cable is subjected to tension, and means to subject the core to tension in response to rearward pivotal movement of the back of the seat about the predetermined pivotal axis.
Advantageously the core of the Bowden cable is connected to a lever, the lever also being connected to at least one Bowden cable having its core connected to parts of a mechanism which move relative to fixed points on rearward pivotal movement of the back of the seat about the predetermined pivotal axis, with the core of the Bowden cables being connected to said fixed point.
Conveniently damper means are provided connected between the squab and back of the seat to damp said rearward pivotal movement of the back of the seat.
Advantageously the damper means comprise a gas spring
Preferably a recliner mechanism is provided connected between the back and sqab of the seat.